Wednesday, October 17, 2018

Experiments with STRIX Free Flight Electric Motor Timer

In the past few weeks I have been experimenting with using a small electric motor timer that I purchased from the RMRC company for under $7. An online friend had sent me a link to this and I ordered a couple of the timers. After receiving the timer I discovered it used the larger JST 2.0 plug in connecting to the battery, so another order was placed for a couple of batteries and a charger that fits this connector. The connector is slightly larger than the connector used on the Eflite planes I have.  In the future I want to replace the connector on the timer with the more standard connector on a sample timer. This would make it possible to use batteries and chargers that many people already have.

Electric Powered Guillow's Cloud Buster

STRIX Timer, motor, and battery
My first test aircraft was an injected foam glider the Guillow’s Skyraider, the motor was mounted on a pylon I constructed out of balsa, everything held together with low temperature hot glue.  The total weight was 56 grams which is too heavy for much of a climb. For a propeller I used one from an Aero Ace biplane I had, it did not overheat the motor like when trying an E20 size propeller. The specifications of the timer call for 6 mm or 7 mm motor, I used 7 mm motors from RMRC which come for in packages of four motors, two wired for clockwise and two counter-clockwise. 

Robbed the Propellers

Comparison of Plug Sizes

Charging Board and AC Power Supply, can use Lipo Battery 3S or 4S

The foam glider might be great if it were lighter, the first flights it only got maybe 20 feet high. I removed some foam from the glider and it started climbing higher. The stability was just okay, it tended to wander around in the sky but it always survived a hard landing.

Electric Foam Glider

For the next plane I wanted to try a balsa plane with a really simple structure, I found a Super Dart in my basement which is similar to Sig Thermal Dart, flat pointy wings. A real short test fight with timer a battery taped on showed that this will climb better with a total weight of 23 grams. The weather has turned windy all the time which is bad for test flying. After another flight in the wind the second flight resulted in the fuselage breaking in multiple places. In the future would like to try this with a basswood fuselage as I would like to find really simple planes for the electric setup.

Super Dart Crash Damage

As I see this timer/motor setup, it would be good for kids flying in a schoolyard, the maximum run is only 10 seconds. You can select between 5,8, or 10 seconds very easily. With the battery that I found to fit the connector  at 220 mah it will give many flights on a single charge. The battery is rather heavy at 6 grams, timer 3 grams, and motor at 3 grams. The increased weight over a rubber motor would explain why crashes on models designed for rubber power would be more damaging. 

Cloud Buster Electric

The last model I have tried was a Guillow’s Cloud Buster built a long time ago. I think this model will work well but again I tried to fly it in way too much wind. First short flight it went too much right but recovered. I added too much weight on left wingtip to correct on second flight and it hit the ground in a left spiral dive breaking the pylon. I started building a new pylon that I can mount the timer and battery inside and have the wing held on by rubber bands. This type of model I have to believe should climb high enough to glide around for an additional 30 seconds or more. Kids do not even have to wind the rubber which should not be a big deal but I find some have trouble. I am looking for other sources of motors and propellers at an inexpensive price. I will write another article as I progress with this farther.

Crash in Progress

Rebuilding Pylon
Update 10/18/2018

It was relatively calm this morning as the sun was coming up but there was frost in the grass. I was determined to get in more test flights on the Cloud Buster I rebuilt the pylon for with the wing now held by a rubber band before work.  First flight at 5 seconds looked alright so went to 8 seconds. The plane had too much right turn, adding clay to wingtip had it going straight with a series of small stalls, taking a small amount off it was better but it seemed to easily circle either direction.  The plane climbs but not very steep, I think more wing area might help. Someone suggested the AMA Maxi Jr might work which I have and will probably try, it has a constant chord wing. The Cloud Buster tapers to thin at the tips.  If I used a lighter battery I think that would help too.

Cloud Buster with New Pylon

Bill Kuhl

Related Links  Link to Timer  
Foam Guillow's Glider   Guillow’s Cloud Buster

Monday, October 8, 2018

Last 2018 Free Flight Contest Minnesota

I was so close to not attending the last 2018 outdoor free flight contest in Minnesota because of the wind prediction and threat of rain. It was cool, dark, and windy at times but the direction gave a good deal of room to drift without getting into trees or corn. For me it was one small problem after another but I still had a great time. At least I should have more time now to get my equipment better prepared for next year.

First Wilbur Flight was high enough for prop to fold

To start flying I decided to take out my Wilbur rubber model that normally flies great but has had issues at the last two contests. Two months ago the center of the wing folded on launch and last contest it would barely climb. The blades were loose on the hub which I repaired and it climbed better in test flight but I did not get up to full winds. At this contest the counter on my winder came loose and the screw was stripped out so I had to count winds and with weird gear ratio that isn’t easy. First test flight it did better than when the blades were loose but after that it just got worse.

Bearing that is Dragging

When I picked up the model with turns left the propeller would barely turn over. The metal sleeve that goes into noseblock hole was loose because it was trying to turn in the balsa. Someone squirted some fuel into the ball bearing thrust bearing that appeared to be dragging. After I glued the sleeve I tried a couple more flights and result was the same. When I got home I looked closer at the ball bearing and it seemed like the two sides of the bearing could be wiggled apart farther than the same type of bearing in another airplane. At times it appeared to turn real hard but not all the time. Replacing the bearing would not be easy as the propeller shaft would have to be broken loose in front where it attaches to the hub.

P30 Still on the Field

For the P30 event I brought my older NJAPF p30 along because I didn’t want to risk my Polecat X in the wind. The fuselage really needs a recovering but the DT line broke just as I tried to wrap it around the rear peg. I didn’t have any line along so I bypassed the DT and hoped for the best. I did not wind it too much because I did not have a counter but I did have a torque meter for P30. Problem was I was not sure what torque would break the rubber. At least I got in 3 official flights and did not lose the model.

No DT Sunday P30

There was another guy flying P30 that did not use a DT because he thought the popoff wing line was causing a trim problem. He made a joke about it being “no DT Sunday” and needing to build a new model. I timed his flight and the model really climbed high, it must have been in enough lift to maintain although it wasn’t climbing any higher. After 2 ½ minutes I lost sight of it but he was able to find the model without a tracker. 

1/2 A Streak Missed Puddle

I flew my ½ A Streak after that just for fun. It was a little harder getting the glow motor running at 50 degrees than when it is 80 degrees. The needle valve needed some adjusting but then it ran well and pulled the plane to a good height. Transition was good and the glide did not stall and was in a gentle right circle, just came down too fast.

My DLG changed trim from last time flying, thought I was getting it readjusted and then it crashed. Like every contest the time just went too fast, I leave rather early because it is a 3 hour drive home. Closing with more pictures from the contest.

Gary Oakin's Rubber Model

Dave Braun's Scale Model Did not Like the Wind

Bill Kuhl

Monday, October 1, 2018

Witch Hawk 500 Free Flight Story

 In the Fall of 2016 I purchased the Witch Hawk 500 kit from BMJR because I wanted to try a larger glow powered free flight, at that time my only glow powered free flight was Cox PeeWee .020 powered. For 2017 the Witch Hawk was to be the One Design Plane at 2017 Nats. I didn’t get mine built for 2017 Nats and barely finished for 2018 Nats. 

2018 Nats Before Picture

Building a larger kit went easier than a small one in that it is harder to break pieces during construction but I had new things to try with this project. I covered it with Polyspan which I had only done before on parts of models, it went pretty well other than trying to find the shiny side. The fuselage was covered with silkspan. I decided last winter I would like to try an airbrush so I ordered the components for a system; it needed some brass fittings for connections. Local auto supply store helped me with that. I sprayed it with the dye that Larry Davidson sells and that went well.  For this large of model, a larger airbrush might have been better but it worked.

Under Construction

Airbrush Compressor

For a larger glow model running on pressure I needed an electric starter attached to a stand, as I have a small car this had to be compact. I found a plastic stool that folded flat and attached my starter and connections to that. To turn it on and off I ordered a trolling motor foot switch.. This was the first time running pressure and I decided to use a Red Cap bladder for my K&B .19 engine with original needle valve. I ran it on a test stand first and it ran pretty well.

Starter Setup

Before the 2018 Nats I had just enough time for some test glides and to run the motor on the plane. At the Nats I picked the first really calm day to test fly. I was nervous, just sure something would go wrong. First short flight it went straight ahead; stalled and came down breaking the propeller. Added tiny bit of rudder trim, next flight went up and transitioned nice but with no wind it glided back into pit area and hit a golf cart. It broke the wing in half but worse than that broke the scroll off my Texas Timer Max IIIa timer.

First Short Flight

Flew Through Golf  Cart

Broken Timer

Broken Wing

Back closer to home I do not have very large flying fields to use so I made the decision to install RC for motor cutoff and RDT. Later I could install an electronic timer to control the servos. To cut the motor, Greg Stewart gave me the great idea to use a valve made for RC smoke systems, Dubro sold this but I had to order through eBay to find one. Fixing the wing was a fair amount of work but it looked pretty good even after spray paint.

RC Install
Recover After Repair

As the flying season is winding down I wanted to fly it again, Saturday morning was darn near calm but there was frost on the ground. I had a little trouble getting the motor running and when I did it was surging a little. I launched it anyway and it went straight ahead and climbed darn near straight up. If it looked like there was any sign it would crash I would cut the motor. It climbed fine so I cut it when it was getting fairly high, it stalled straight ahead but had plenty of altitude to recover and as it leveled out it went into a nice glide to the right and landed. 

Frost in the Grass

My hands were cold and I needed to be somewhere so I did not fly it again. I was really happy. I know people have told me larger free flights are easier than small ones but I know they can crash harder also.

Bill Kuhl

Tuesday, September 11, 2018

Cox Tee Dee .010 and Nostalgia Thoughts

Jokingly I sometimes tell people I started my second childhood early; that is why I play with model airplanes. Besides reliving my childhood I try to experience the good times in the past that other people enjoyed with model airplanes that I missed out on, mainly free flight model airplanes. I have built some of the older free flight planes and acquired older glow engines as well CO2 engines. 

In free flight I prefer the smaller glow powered planes and there are events that require a Cox TeeDee .020 engine that is no longer being manufactured. I have been having a great time flying a Cox PeeWee .020 powered PeeWee 30 free flight model, so thought I might try .020 Replica or Payload event. I have two Cox .020 TeeDees on the way and also two Cox .010 TeeDees. From my childhood I can remember gazing at a Cox TeeDee .010 in hobby shop display case but it was just too expensive for a kid.

PeeWee .020 Powered Free Flight

Last year I started flying an electric powered control line model but after crashing on the first flight because of the wind and too long of lines, I decided to build ½ A model powered with Cox Babe Bee. This was my first real start in model aviation at 10 years old. Like almost everyone says remembering the fun with model aviation in their childhood, these were great memories. Last week I flew my ½ A Dewey Bird for the first time but I had used too heavy metal lines that were maybe too long also.  As an adult, I want to take this a little more serious and get details dialed in closer to the optimum.

Dewey Bird 1/2 A Control Line

There appears to be a good amount of interest by many people in acquiring items from the past, I read this article from Forbes and quoted this explanation:

“As such many people have looked back to simpler times and been attracted to products from that past that remind them of when life wasn’t so complicated.

This interest continues with more new “old” products where people just want something that is straightforward, basic, and tangible in a way that modern technology just can’t offer.”

I watched this video about flying some old plastic ½ A control lines and found the comments very interesting. The theme that was repeated was how great the memories were and many of the kids that did this did well in later life.

Antique Cox Control Line Plane's History and flights by NightFlyyer

Sample of Comments:

“Everyone I know who flew these as a kid, grew up to be decent, hard working people.  Great memories.”

“You know what ? you are so correct i am an engineer repairing photo copiers, like all my friends who i used to fly with we are all engineers owning our own homes all worked hard all our lives so true.”

“ After reading your comment, I did a quick mental role call, and 6 out of 7 of my friends that flew these, were and are successful. 2 became airline pilots, one worked at JPL and all were successful and respected in their given fields.”

 Bill Kuhl

Friday, September 7, 2018

Witch Hawk Repair & RDT

I was reading an exchange on Facebook recently that started out with someone giving a negative opinion of the use of Remote DT in free flight competition. This is not the first time I have heard comments like this and I can understand why people feel that way. Some people didn’t even like the idea of trackers but I think for the majority of the free flight population trackers are essential equipment. 

Witch Hawk 500 Repaired

The longer I fly free flight airplanes the more I appreciate the challenge of making a model airplane fly with no control from the ground. It can be a lot harder than it looks to get a model adjusted to fly consistently without control. At times it is frustrating not to be able to save the model from a spiral into the ground that results in more repairs. The rational for not liking RDT was the model was not truly flying free if you could bring it down at will; they also liked the thrill of the complete chase of the model. Another comment that came up was a dislike for auto surfaces, something I doubt I will get to that level in model complexity to use.

RC Install Underway

In my Witch Hawk 500 that broke the wing in half at 2018 Nats I am installing RC for DT and to cut the engine. When I feel the plane is trimmed I will attach an electronic timer to the engine cut off servo. The largest field I fly from in local area is 44 acres and the field has trees and powerline around the edges. Flying at the Minnesota contest field there are trees on one side that I really want to stay out of.

I was checking on eBay for mechanical timers and did not see a single Texas Timers timer, really not much of anything. Also looking for a Cox TeeDee .020 and have gotten my bid up way higher than I wanted too.

Dewey Bird and Stooge

Last evening I did fly the Dewey Bird ½ A control line model. I made a really crude stooge to release it with but it worked okay. The lines I had .012 were too heavy and maybe too long at 35’, tension was not great but then it is a small model. With my free flight experience I am getting more concerned with details, finding out the hard way details matter.

Bill Kuhl

Friday, August 31, 2018

Learning From Model Aviation & New Challenges

I was really overwhelmed by the number views (700) to my last blog post about my Wilbur rubber model, the repair was finished and I flew the plane last weekend. I covered the center section with ¼ mil Mylar with tissue over top; this kept the tissue tight in really humid conditions.

Dewey Bird Control Line

Wilbur Flying in the Fog

After the Free Flight Nats was over I wanted to try control line flying again, last fall I was flying an electric powered control line that worked well after initial problems. This year it flew fine but I have been hesitant to try any stunting other than wingovers because it seems rather fragile. So last winter I had ordered a simple ½ A glow powered control line the Sig Dewey Bird. Construction went well but then I was hesitant to install blind nuts because of the challenge it has been for me in the past. This time it went worse in that I got epoxy inside of the threaded area and twisted off a bolt. I tried drilling out the bolt but my drill bit barely scratched the surface. I started asking questions to a free flight listserve group and I received a lot of good suggestions although most were what to do before I twisted the bolt off, like heating the epoxy or plugging the hole before the epoxy. At the local hardware store I bought a cobalt drill bit which did drill through the metal and I tapped it for 2-56. 

Piston and Cylinder Cox Baby Bee .049

Someone gave me a Cox Baby Bee .049 that would not turn over with a rather large wood propeller. I figured the propeller over heated the engine but in asking questions I found out that people run even larger propellers on reed valve Cox .049 engines in the Texaco event. When I took the engine apart the bottom of the piston that connects to the connecting rod looked like it exploded. From my stash of old engine parts I found another piston and pushed out the old one. After putting the engine back together it ran great after a short time, it will be used in the Dewey Bird. With my electric control line I added tip weight that I never put in, it really helped the tension on the line; for the Dewey Bird I used a nickel for tip weight. 
Assembled Sofa

Model Kit Instructions

Furniture Assembly Instructions

A couple of weeks ago I helped a friend assemble some furniture, it went pretty well for me but I have to believe that having built model airplanes was a real help. I have lots of experience reading directions and diagrams with model airplanes. With so much purchased online being able to assemble anything can save a lot of money compared to paying someone to do it. I found this quote from Business Insider about “spatial reasoning ability” interesting:

 “It's no surprise that high verbal and math SAT scores at a young age might predict future success, but when you add a test for spatial reasoning ability to the mix, you get an even better predictor of someone's future accomplishments, creativity, and innovative potential, a recent study found.” 

G-12 Catapult Glider
This week I finished up building the G-12 catapult free flight glider which will be used in Dick Bertrand’s Free Flight Rescue Program. It went together really well as most parts are designed to lock together. In doing some hand launches with the glider it appeared to be really stable. Look for more to come about this glider. 

Bill Kuhl

Related Links Electric U-control